Microsoft Security Bulletin MS14-040 - Important

In this article

General Information

Executive Summary

This security update resolves a privately reported vulnerability in Microsoft Windows. The vulnerability could allow elevation of privilege if an attacker logs onto a system and runs a specially crafted application. An attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability.

This security update is rated Important for all supported releases of Microsoft Windows. For more information, see the Affected and Non-Affected Software section.

The security update addresses the vulnerability by correcting the way that the Ancillary Function Driver (AFD) validates input before passing the input from user mode to the Windows kernel. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability later in this bulletin.

Recommendation. Most customers have automatic updating enabled and will not need to take any action because this security update will be downloaded and installed automatically. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871. For customers who do not have automatic updating enabled, the steps in Turn automatic updating on or off can be used to enable automatic updating.

For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update at the earliest opportunity using update management software, or by checking for updates using the Microsoft Update service. The updates are also available via the download links in the Affected Software table later in this bulletin.

See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.

Knowledge Base Article

Affected and Non-Affected Software

The following software has been tested to determine which versions or editions are affected. Other versions or editions are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, see Microsoft Support Lifecycle.

Update FAQ

There are multiple update packages listed for Windows 8.1 and Windows Server 2012 R2. Do I need to install all the updates listed in the Affected Software table for the software?No. Depending on how your system is configured to receive updates, only one of the updates for Windows 8.1 or Windows Server 2012 R2 will apply.

For systems running 8.1 or Windows Server 2012 R2:

Update 2961072 is for systems that already have the 2919355 (Windows 8.1 Update) update installed.

Update 2973408 is for systems without the 2919355 update installed. Note that the 2973408 update is only available for customers managing updates using Windows Server Update Services (WSUS), Windows Intune, or System Center Configuration Manager.

For Windows 8.1, Windows Server 2012 R2, or Windows RT 8.1 are there any prerequisites for the 2961072 update?Yes. Customers running Windows 8.1, Windows Server 2012 R2, or Windows RT 8.1 must first install the 2919355 (Windows 8.1 Update) update released in April, 2014 before installing the 2961072 update. For more information about the prerequisite update, see Microsoft Knowledge Base Article 2919355.

I am using an older release of the software discussed in this security bulletin. What should I do?The affected software listed in this bulletin has been tested to determine which releases are affected. Other releases are past their support life cycle. For more information about the product lifecycle, see the Microsoft Support Lifecycle website.

Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, see the Microsoft Worldwide Information website, select the country in the Contact Information list, and then click Go to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the Microsoft Support Lifecycle Policy FAQ.

Severity Ratings and Vulnerability Identifiers

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the July bulletin summary. For more information, see Microsoft Exploitability Index.

A vulnerability exists in the Ancillary Function Driver (AFD) that could allow elevation of privilege. An attacker who successfully exploited this vulnerability could execute arbitrary code and take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2014-1767.

Mitigating Factors

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

An attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

FAQ

What is the scope of the vulnerability?This is an elevation of privilege vulnerability.

What causes the vulnerability?The vulnerability is caused when the Ancillary Function Driver (AFD) improperly processes user-supplied input leading to a double free scenario.

What is the Ancillary Function Driver?The Ancillary Function Driver (AFD) supports Windows sockets applications and is contained in the afd.sys file. The afd.sys driver runs in kernel mode and manages the Winsock TCP/IP communications protocol. This Winsock kernel interface provides access to the TDI transports.

What is the Transport Driver Interface?The Transport Driver Interface (TDI) defines a kernel-mode network interface that is exposed at the upper edge of all transport protocol stacks. The highest level protocol driver in every such stack supports the TDI interface for still higher-level kernel-mode network clients. For more information about the TDI Component, see the MSDN article, Transport Driver Interface.

What might an attacker use the vulnerability to do?An attacker who successfully exploited the vulnerability could run arbitrary code in kernel mode. An attacker could then install programs; view, change, or delete data; or create new accounts with full administrative rights.

How could an attacker exploit the vulnerability?To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and take complete control over the affected system.

What systems are primarily at risk from the vulnerability?Workstations and terminal servers are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do?The update addresses the vulnerability by correcting the way that the AFD validates input before passing the input from user mode to the Windows kernel.

When this security bulletin was issued, had this vulnerability been publicly disclosed?No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Detection and Deployment Tools and Guidance

Several resources are available to help administrators deploy security updates.

Yes, you must restart your system after you apply this security update.

Removal information

WUSA.exe does not support uninstall of updates. To uninstall an update installed by WUSA, click Control Panel, and then click Security. Under Windows Update, click View installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

WUSA.exe does not support uninstall of updates. To uninstall an update installed by WUSA, click Control Panel, and then click Security. Under Windows Update, click View installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, and then under Windows Update, click View installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, and then under Windows Update, click View installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, and then under See also, click Installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, and then under See also, click Installed updates and select from the list of updates.

Other Information

Microsoft Active Protections Program (MAPP)

To improve security protections for customers, Microsoft provides vulnerability information to major security software providers in advance of each monthly security update release. Security software providers can then use this vulnerability information to provide updated protections to customers via their security software or devices, such as antivirus, network-based intrusion detection systems, or host-based intrusion prevention systems. To determine whether active protections are available from security software providers, please go to the active protections websites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Disclaimer

The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.